might and may

 i know that may and might similar in meaning. and they express the idea of maybe, perhaps. and i know maybe it is wrong: might is future of may. i don't know the red line between may and might.

for instance; It is possible that Ali will open a savings account = Ali may open a savings account.

but why don't we say Ali might open a savings account. i suppose there is an other difference between them. do you know and help me about it?

I'd say "might" indicates a still remoter/weaker possibility, but as Calif says, you can use either one without much difference in meaning.

Vinjenpa wrote:

I learnt from a writing tips list I belong to that there is a definite differnece between these words: may = permission might = possibility can = ability

Reminds me of a schoolmaster:

Boy: Please sir, can I leave the room?

Master: You can, but you may not.

Also in traditional grammar, may is present and might is past:

He says he may come.

He said he might come.